Sunday, August 27, 2006

This afternoon I used the department Windows box to upload some photos and try my hand at making panoramas using Autostitch. The program was remarkably easy to use, but unfortunately is only available for Windows. Here's the panorama from Shanghai:This is outside of the entrance to the People's Museum, in Renmin Square (People's Square). I don't know what's up with the green part in the middle-left, but not bad for a first try, eh? It wasy very cloudy and horribly smoggy the entire time I was there; let's put it this way: there was apparently a full moon while I was there, but I have no memory of ever being able to see any moon at all. I took the pictures that comprise this panorama my first day in the city (after having spent a week on the Fudan campus). It was nice to see a real city ... the Fudan campus was rural enough (which is to say, not terribly, but still) that the cicadas were deafening. I like all of the crazy looking buildings... Shanghai is still in the middle of a huge construction boom, but apparently (and I have no way of knowing if this is true or not) many of these new buildings are fairly empty... but they look pretty and China can tout about how progressive they are.

Tuesday, August 22, 2006

There's this red car that has been parked—badly—outside of my apartment since the day I moved in nearly a year ago. I've watched dead leaves gather around its ever-flattening tires, snow and ice take longer to melt under its bumper than elsewhere, and more recently, spider-webs grow on its front grill and wheels. I used to be mildly annoyed that I have to walk around it every morning and every night, but now, I want it gone. It is no longer a mild amusement: now, it's in my way. You see, now I have a car, and I want that parking spot. But no, no no, it has a parking sticker saying that not only does it belong to one of my everso delightful neighbors, but also that it can legally keep its rotting ass right there.

Some people would try to draw an analogy here, something about how people with great talents and skills never seem to fully appreciate or use what they have while the "rest of us" have to work for what we get. Or something about having cake? Or is it ice cream? Mmm... ice cream...

Thursday, August 17, 2006

I have this vague memory of kindergarten, or elementary school, or sometime, when all the other kids were really into the planets. Me? I really couldn't care less. They seemed so... boring. I simply didn't care which order they came in, or when they were discovered, or what color they were, or whatever other nonsense people could come up with to talk about regarding these spheres with funny names.

It naturally follows that fifteen or so years later I decided to become an astronomer.

Now when I hear about "planets," I don't normally think first of our own Solar System. About 200 planets orbiting stars not our own have been discovered to date. As much has been speculated, but very little is actually known, about planet formation, it is very interesting indeed to think we might someday be able know what distributions of mass, distance from the parent star, brightness of planet star, etc. etc. planets take on. But our own Solar System? It's essentially one data point. Granted, it's the data point we know (and care) the most about, and since it's the one we can study the most about, we certainly should.

And so this week I have been getting a bit of a deja vu: "do you think Pluto should be a planet?" Well, the thing is... I don't really care. Neither, really, does any other astronomer. It's a definition. Nomenclature. Convention. Perhaps if we knew exactly how bodies orbiting stars formed then we could discover there is an obvious way of defining a "planet," but, well, we don't.

Personally, I think I like the current IAU proposal (I've posted the text of the actual proposed definition below). Like most people, my reaction went something like: "Ceres? ... Charon?!" But after reading the proposal, it mostly makes sense now. I think I can see what they were thinking, which is... good.

The reason I like the proposal is two-fold. First of all, I like that it acknowledges the eight "classical" planets. The terrestrials (Mercury, Venus, Earth, and Mars) and the gas giants (Jupiter, Saturn, Uranus, Neptune) just seem like the should be considered separately from the other minor bodies in the solar system. My real attraction to the phrase "classical planets," however, is that these are not the classical-in-the-real-historical-as-in-Greek sense: the word "planet" originally meant "wandering star" and referred, understandably, to the objects that moved across the sky in a detached manner from the background stars. The original seven planets were the Sun, the Moon, Mars, Mercury, Jupiter, Venus, and Saturn. Why else would there be seven days in the week?

My second reason for liking the proposed definition is that it appears to be physically motivated. Even if the proposal is not approved, people around the world are not merely aruging over "oh no! they're demoting Pluto!! poor pluto!" but actually being forced to think about the physical differences between different kinds of objects. Why is our Moon not a planet, but Charon is? (Hint: the center of mass for the Earth-Moon system is beneath the Earth's crust, while the center of mass for the Pluto-Charon system is not located inside either rock.) And, of course, it amuses me to no end to think of all the hapless souls in the non-scientific general public who, for whatever reason, have "always been interested in astronomy" and are now actually being forced to think a little bit about the conventions and panoramas they were taught in third grade.

Now, I didn't go through the "dinosaur stage" when I was six years old, either, but at least no one can count the current number of dinosaurs on their fingers. On the other hand, not everyone openly acknowledges that the dinosaurs actually existed ...

Current proposed definition of planet from the IAU:Draft Resolution 5 for GA-XXVI: Definition of a Planet

Contemporary observations are changing our understanding of the Solar System, and it is important that our nomenclature for objects reflect our current understanding. This applies, in particular, to the designation "planets". The word "planet" originally described "wanderers" that were known only as moving lights in the sky. Recent discoveries force us to create a new definition, which we can make using currently available scientific information. (Here we are not concerned with the upper boundary between "planet" and "star".)

The IAU therefore resolves that planets and other Solar System bodies be defined in the following way:

(1) A planet is a celestial body that (a) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape[1], and (b) is in orbit around a star, and is neither a star nor a satellite of a planet.[2]

(2) We distinguish between the eight classical planets discovered before 1900, which move in nearly circular orbits close to the ecliptic plane, and other planetary objects in orbit around the Sun. All of these other objects are smaller than Mercury. We recognize that Ceres is a planet by the above scientific definition. For historical reasons, one may choose to distinguish Ceres from the classical planets by referring to it as a "dwarf planet."[3]

(3) We recognize Pluto to be a planet by the above scientific definition, as are one or more recently discovered large Trans-NeptunianObjects. In contrast to the classical planets, these objects typically have highly inclined orbits with large eccentricities and orbital periods in excess of 200 years. We designate this category of planetary objects, of which Pluto is the prototype, as a new class that we call "plutons".

(4) All non-planet objects orbiting the Sun shall be referred to collectively as "Small Solar System Bodies".[4]

Notes:

1 This generally applies to objects with mass above 5 x 1020 kg and diameter greater than 800 km. An IAU process will be established to evaluate planet candidates near this boundary.

2 For two or more objects comprising a multiple object system, the primary object is designated a planet if it independently satisfies the conditions above. A secondary object satisfying these conditions is also designated a planet if the system barycentre resides outside the primary. Secondary objects not satisfying these criteria are "satellites". Under this definition, Pluto's companion Charon is a planet, making Pluto-Charon a double planet.

3 If Pallas, Vesta, and/or Hygeia are found to be in hydrostatic equilibrium, they are also planets, and may be referred to as "dwarf planets".

4 This class currently includes most of the Solar System asteroids, near-Earth objects (NEOs), Mars-, Jupiter- and Neptune-Trojan asteroids, most Centaurs, most Trans-Neptunian Objects (TNOs), and comets. In the new nomenclature the concept "minor planet" is not used.

Sunday, August 13, 2006

As my parents are coming into town on Tuesday, and spending the night at my place, I clearly need to clean up my apartment so I don't hear about how much of a slob I am for the next 47 years. And as I didn't particularly have any other plans today, the idea was nominally to do laundry while turning my apartment upside down and shaking it, perhaps with some bleach, so that it is as spotless as possible.

Needless to say, I stumbled upon the brilliant idea this afternoon (when faced with the choice of Doing Stuff or sitting on my couch watching Babylon 5 or The Twilight Zone) that my purposes would be much better served if I waited until tomorrow to go on a cleaning rampage. So I watched a DVD, wasn't in the mood to have my laptop on my lap for another two hours, and yet still had to come up with something to put off the impending doom.

So I exercised. I lifted weights, I went for a run (nearly ten whole minutes!), and I even stretched. Now, you have to realize, this never happens. Every few weeks, I resolve to "get in shape" or to "go running every other day" or to "at least lift weights to work on alleviating RSI." But it never happens. Even when I do get the occaisonal whim to try to do something physical, it's not strong enough to, you know, actually get off the couch and do something about it.

Today the random though got took control of me when I started off by trying to meditate for ten minutes. I really like the idea of meditation, of solidifying the connection between the mind and the body. This is a connection that is often ignored, even eschewed, in western culture. It's got a bad reputation. To concentrate on or care about such an intangible is what hippies do (and no one actually takes hippies seriously). Even simply caring about the capabilities and explorations of the mind is thought of as weird, or linked with drugs (and, as we all know, drugs are bad). The whole language surrounding how the mind and the body are linked reeks in fou-fou nonsense (e.g., "energy flow") that can't actually be backed up by, you know, science. Nevermind that that's because science just hasn't gotten there yet.

I first became interested in the idea of "meditation" (the term I'll loosely use for the idea of exploring the mind-body connection, though they are clearly distinct) when in Thailand for the first time, in January 2004. My father and I were motorcycle riding around the mountains in northern Thailand for about two weeks, and since this was a vacation after all, we had an hour-long massage each afternoon. Sometimes two. I got hooked on the Thai massage; it's an interactive experience, full-body (starting at the feet and moving up to the head and face), complete with various stretches. "Normal" (i.e., "Swedish") massage often focuses on relaxation, on having you be as calm and peaceful and out-of-it as possible by the end. Thai massage is entirely different; at the end of a good Thai massage, I feel indescribably alive, ready and able to do anything and everything, envigorated and enthused about life itself. This result, to me, is the desired outcome of a deep meditation. I want to learn how to funnel what energy I have into action, into thought.

The basic idea is simple: if I can become a happier, more productive, more energetic person by focussing on not merely what my mind is doing, but also my body, then, well, I should give it a try. I might even become healthier in the process.

Obviously, it's unreasonably, on a whole host of levels, for me to have a daily Thai massage while in Columbus, Ohio and trying to change the prefix adhered to my name. I know I am, in general, guilty of completely ignoring my body until it starts complaing that it wants something or doesn't like something else. Most of the time, it's just this thing I use to take my senses from one place to another, and, most of the time, said senses are merely used as information gatherers. Not exactly a two-way channel. Sure, there's comfort food, which isn't exactly healthy per se, but it's amazing how much better a bag of Doritos can make me feel (let alone a Coke or a nice cup of coffee, but caffiene is a whole other matter for consideration). And it's true, like most people, I get a mild euphoria after running for even five minutes (but it's very difficult to use that as a motivating factor before-hand). Similarly, I have also considered taking up dancing; the summer I spent at Caltech, I went swing dancing several times, though I can't definitively say that was a source of my high productivity and energy levels that summer.

So... what about meditation? How does it work? Everything I can find on the internet is about "relaxing" and "letting it all go" and "de-stressing." Uhm, no thanks. While sitting Indian-style with good posture does feel good for a little while, it doesn't exactly make me want to go figure out how the universe works. Is there a type of "meditation" that energizes instead of puts to sleep?

More along the lines of (mentally) concentrating on physical movement, there's qi gong, which I have mostly heard about from a friend for whom it has been most effective. I have had trouble with RSI (repetitive stress injury) for several years; while it's not as bad now as it used to be (at one point I was unable to open plastic bottles or doors with circular knobs) I still have to be careful not to hurt myself. I don't know much about qi gong, but I am interested in learing more. Apparently, all this would require is getting up early on Wednesdays, as the OSU medical center has recently started offering free weekly classes on qi gong.

But all of these ideas require actually doing something in order to, you know, do. And garnering the motivation to do stuff isn't exactly one of my fortes lately ...

Wednesday, August 09, 2006

I went through this stage once where I didn't read the news, at all, for about three years. The entire list of reasons is enough for a whole other post, but one contributing factor was certainly that every news article I have ever read about something (or someone) I actually know something about has made me want to scream due to mistakes ranging from raw factual errors or subtle misinterpretations.

In a nutshell, the Hubble constant, H0, relates how fast, v, an object (say, a galaxy) is moving away from us to its distance, d, from us in a simple way: v = H0d. The neat part is that, with very few other assumptions thrown in, the Hubble constant also tells us the age of the universe. So, we want to know this constant pretty badly. Velocities are fairly easy to measure, but distances... distances are hard. Relative distances aren't all that bad (e.g., "this galaxy is about twice as far away as that galaxy") but absolute distances are very difficult (e.g., "that galaxy is 50 kiloparsecs away").

For a long time, people have been anchoring their distance scales to the Large Magellenic Cloud, or the LMC. (For those of you who, like me until a year ago, never realized that the southern and northern hemispheres really do see different parts of the sky, the Large and Small Magellenic Clouds are two small dwarf galaxies orbitting our own Milky Way. They are so named because when Magellen's crew went sailing through the southern hemisphere, they were kind of confused as to why these two clouds always seemed to move with the sky, see...) The LMC kind of makes sense: it's close, and therefore easy to see, so it should be fairly easy to get a distance to. Right? Wrong.

So as I don't want to get into a whole discussion of how distances are measured, suffice it to say, for now, that people are always looking for new, independent measurements. The exciting thing about the M33 distance is that it's just that: a direct measurement of the distance to M33, independent of this fuzzy object in the southern sky. Working backwards, they are able to estimate the Hubble constant, which, sure, while 15% lower than what the HST Key Project got, is actually not unreasonable if you take into account the errorbars.

What all of this buzz has been forgetting, though, is that a "new" calculation of the Hubble constant ... isn't that exciting. I mean, it is, because it's the Hubble constant, which is exciting in and of itself, but the fact that people are getting all worked up over it (whereby "people," I clearly mean the media, which doesn't really count, but anyhow) just goes to show how remarkable it is that there has been a fairly agreed upon value for the last five-ish years.

And here you have it: published values of the Hubble constant over the last thirty-ish years. References can be found here. The big dot there on the right is the M33 value; its errorbars should be roughly the same as the HST ones (70% of which are due to systematics from not knowing the distance to the LMC, by the way). The supernovae paper listed several values, only one of which I've plotted, and they specifically state that their errors do not account for systematics. The WMAP results should be taken skeptically, as they fit for many cosmological parameters, and it's rather tricky to sort out all of their priors and other assumptions that go into H0 in particular.

Bottom line: the "new" value of the Hubble constant isn't exactly new, per se; it's just another step that's being taken in figuring out exactly how to measure distances to far away objects.

Tuesday, August 08, 2006

I'm in the middle of composing a blog post—mostly in my head at this point—on the infamous Hubble constant and how distances are measured in astronomy and the implications said distances have on cosmology, but as that takes work, and work takes time and effort and focus, I'll instead let you know about some other fun stuff...

For example, the age of the universe is apparently increasing exponentially. First, it was thousands of years old because we could trace back the geneologies in the Bible and add up the years. But that first week is rather tricky, and then we started being able to date fossils, and, later, rock formations, which were milions of years old, and the age of the universe has to be at least as old as the age of the Earth. And then came Hubble and galaxies moving away from us and all sorts of things like that, and now the universe is billions of years old.

For your viewing convenience, I've replotted their data on a log plot:

Friday, August 04, 2006

I think one reason I might be used to coming in on the weekends is because I don't always seem to get things done during the week. All of today, as well as most of yesterday afternoon, I've been trying to convince myself to write a script/code/thing that goes through our data and removes lines from the files corresponding to data which just isn't there (e.g., if we're missing for a year for a given object). This is really not a difficult task. And yet, as I've only sort of written a few lines of it, I'll probably come in tomorrow to do it. And then to start reducing the other set of data (the same stuff, but taken in a different wavelength).

It's funny, cuz I feel rather motivated right now, just not to, you know, do anything. Then I made the mistake of eating lunch, and all of that murky substance called "motivation" I had found in multiple cups of morning coffee and good conversation was instantly and irrevocably lost. How annoying. On the other hand, I remembered to bring both my camera and my USB stick to campus today, and my Chinese officemate who chews with his tongue instead of with his teeth and is therefore one of the reasons I tend to get homicidal if I am in my office around mealtimes remembered to bring his MacBook. See, my old decripid version of iPhoto doesn't realize that movies are a perfectly acceptable thing to download off of a camera, and therefore I have quite a number of movies that have just been biding their time on the camera instead of on the internet, which is where they really want to live. So here's one for you, complete with motivational communist music (such as was being piped into the train from Hue to Ha Noi, Viet Nam), so be sure to turn your volume up!

Today's other highly motivating event was the thesis defense of Rik, in that I got to think, "Ooh, I wanna change my name!!" and to consider the fact that sometime in the next four years I should figure out exactly how one transitions from being a student to an independent scientist. On the other hand, lots of sugar and a touch of champagne aren't exactly the most motivating factors of a lazy Friday afternoon.

In any case, it's now time for AstroMovie, so ... I 'll finish writing that code ... later?

Tuesday, August 01, 2006

I can't remember the last time I felt like everything in my life was simply going well. It's a strange and wonderful feeling. I highly recommend it.

Anyhow, seeing as how my paper was accepted by ApJ (the Astrophysical Journal) last night, I might as well start babbling about my next project with Kris Stanek.

The main goal of this project is to have something short, sweet, and fun, from which I can learn a lot and publish a paper. There are some near-infrared data lying around from 2000 through 2002 that some guys in our department took in order to look at one object, but they never got around to analyzing the rest of the data. So, we've got a bunch of images of the center of the Milky Way, and now we can look for variable sources, such as binary stars or pulsating stars or other crazy things. One of the exciting things about the cluster of stars at the center of the Galaxy is that there are both old and young stars (which is unusual---usually all of the stars in a cluster are the same age) and so there can be a lot of crazy stuff going on.

The way we are looking for variable stars is with a method called image subtraction. It's totally nuts that this works; we can often get fairly good light curves (graphs of how the brightness changes with time) of stars in regions so crowded that we can't even resolve the individual stars. To do this, we first make a reference image from some of the really good looking images in the set, and then subtract all of the other images from the reference (hence image subtraction). Stars that don't change in brightness ("vary") as time passes from image to image don't show up in the subtracted images, but ones whose brightnesses change do show up. We then, with the help of some black magic and code, can plot the light curves of the stars in the field.

Then comes the fun part. Lots of variable stars vary with some period; for instance, an eclipsing binary varies according to how long it takes for the two stars to go around one another. So, we just plop the data into a program and fiddle with it. This is what I spent this afternoon playing with. It's like connect-the-dots on steroids. The really fun part of it is playing with the phase-modulator, which folds the lightcurve up according to some phase, which I then get to futz around with.

The current plan is to have lightcurves for all of the sources in the field by tomorrow, or maybe Thursday. Not bad considering we started yesterday morning ...

And then I get to spend a month tweaking all sorts of parameters and redoing everything many many times and looking at lightcurves all squinty-eyed until I don't know left from right (I already don't know up from down) and we have everything all set. And much to Kris's chagrin, I don't think we'll actually have the paper finished by next Friday ...

about me and my blog

I'm a graduate student in astronomy in the cloudy midwest. I have a "cozy" little apartment and an office desk by a big window. If I find something interesting to write about, I usually do; if everything is really boring, I write about that as well (unless I don't).